Ah, I see now, that makes sense.
I did mean a second mapper but when I wrote that I didn't realize I
could actually do that. After reading the docs, I know now ;-)
Thanks again for your help Michael....great stuff you've got here.
Cheers,
Jon
On May 27, 7:51 am, Michael Bayer <mike...@zzzcomputing.com> wrote:
> On May 26, 2010, at 8:01 PM, ObjectEvolution wrote:
>
>
>
> > Thanks for the input Michael. I think the polymorphism is messing
> > things up...just a hunch. Your suggestion didn't work but this ended
> > up working:
>
> > 'children': relation(Category,
>
> > primaryjoin=and_(TABLES.CATEGORY.c.id==TABLES.CATEGORY.c.parent_id,
>
> > TABLES.BASE.c.deleted==False),
> > backref=backref('parent',
>
> > remote_side=(TABLES.CATEGORY.c.id)),
> > ),
>
> > Does that make sense? I was excited that it worked at first but then I
> > wasn't quite sure how it worked. How does it recognize TABLES.BASE?
>
> if the mapper is against the join of base->category, then both tables are
> present in the FROM clause using a join.
>
>
>
> > I'm thinking that it might be best to have a mapping instead of what
> > we have now given our polymorphism. Thoughts on that?
>
> not sure what this means. I was going to also suggest having a second mapper
> against Category that filters out the "deleted" rows, is that what you mean ?
>
>
>
> > On May 26, 3:00 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
> >> On May 26, 2010, at 4:56 PM, ObjectEvolution wrote:
>
> >>> Hi,
>
> >>> I've got the following tables in my app (only showing applicable
> >>> columns here) storing categories for my app:
>
> >>> Base
> >>> - id (int) PK
> >>> - deleted (int) - 0/1 as a value
>
> >>> Category
> >>> - id (int) PK/FK - refers to Base.id
> >>> - parent_id (int) FK - self-referential to Category.id
>
> >>> I then have a Category object, which inherits from Base. All's good.
>
> >>> What I'm trying to do is when I get my Category object I only get
> >>> children which aren't deleted=1. My original property in my mapper was
> >>> this:
>
> >>> 'children': relation(Category,
> >>> primaryjoin=TABLES.CATEGORY.c.id==
> >>> TABLES.CATEGORY.c.parent_id,
> >>> backref=backref('parent',
>
> >>> remote_side=[TABLES.CATEGORY.c.id]
> >>> ),
> >>> ),
>
> >>> Which works fine but gets everything. So I changed it to this:
>
> >>> 'children': relation(Category, secondary=TABLES.BASE,
>
> >>> primaryjoin=TABLES.CATEGORY.c.id==TABLES.CATEGORY.c.parent_id,
>
> >>> secondaryjoin=and_(TABLES.BASE.c.id==TABLES.CATEGORY.c.id,
>
> >>> TABLES.BASE.c.deleted==False),
> >>> foreign_keys=[TABLES.CATEGORY.c.id],
> >>> backref=backref('parent',
>
> >>> remote_side=[TABLES.CATEGORY.c.id]
> >>> ),
> >>> ),
>
> >> the way "secondary" works is:
>
> >> parent -> primaryjoin-> secondary -> secondaryjoin -> child
>
> >> So primaryjoin has to be in terms of "category" and "base", as does
> >> secondaryjoin. Also you don't use "remote_side" with "secondary".
> >> "foreign_keys" are also usually implicit from your Table metadata and its
> >> rare these are needed (unless an error message asks for them, which often
> >> indicates something else is the actual issue).
>
> >> what you have here really does not appear to be a many-to-many
> >> relationship, its one-to-many/many-to-one. So if you want the
> >> relationship to add a where criterion for the "base.deleted", you likely
> >> just want to use and_() all within the primaryjoin.
> >> and_(category.id==category.parent_id , base.deleted==False,
> >> base.id==category.id).
>
> >>> and I get nothing. Not a single object. Is my issue:
>
> >>> 1. Foreign key related?
> >>> 2. Join related?
> >>> 3. Developer related?
>
> >>> Any help here is appreciated.
>
> >>> Thanks!
>
> >>> Jon
>
> >>> --
> >>> You received this message because you are subscribed to the Google Groups
> >>> "sqlalchemy" group.
> >>> To post to this group, send email to sqlalch...@googlegroups.com.
> >>> To unsubscribe from this group, send email to
> >>> sqlalchemy+unsubscr...@googlegroups.com.
> >>> For more options, visit this group
> >>> athttp://groups.google.com/group/sqlalchemy?hl=en.
>
> > --
> > You received this message because you are subscribed to the Google Groups
> > "sqlalchemy" group.
> > To post to this group, send email to sqlalch...@googlegroups.com.
> > To unsubscribe from this group, send email to
> > sqlalchemy+unsubscr...@googlegroups.com.
> > For more options, visit this group
> > athttp://groups.google.com/group/sqlalchemy?hl=en.
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalch...@googlegroups.com.
To unsubscribe from this group, send email to
sqlalchemy+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
